From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH v6 0/7] Add virtio-iommu driver Date: Wed, 12 Dec 2018 11:35:45 +0100 Message-ID: <20181212103545.GV16835@8bytes.org> References: <20181211182104.18241-1-jean-philippe.brucker@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id E925B4A1DD for ; Wed, 12 Dec 2018 05:35:48 -0500 (EST) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id wq+MHRjwsDig for ; Wed, 12 Dec 2018 05:35:47 -0500 (EST) Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 850E64A1DC for ; Wed, 12 Dec 2018 05:35:47 -0500 (EST) Content-Disposition: inline In-Reply-To: <20181211182104.18241-1-jean-philippe.brucker@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: Jean-Philippe Brucker Cc: virtio-dev@lists.oasis-open.org, kevin.tian@intel.com, lorenzo.pieralisi@arm.com, tnowicki@caviumnetworks.com, mst@redhat.com, marc.zyngier@arm.com, linux-pci@vger.kernel.org, jasowang@redhat.com, will.deacon@arm.com, robin.murphy@arm.com, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, robh+dt@kernel.org, bhelgaas@google.com, frowand.list@gmail.com, kvmarm@lists.cs.columbia.edu, devicetree@vger.kernel.org List-Id: kvmarm@lists.cs.columbia.edu Hi, to make progress on this, we should first agree on the protocol used between guest and host. I have a few points to discuss on the protocol first. On Tue, Dec 11, 2018 at 06:20:57PM +0000, Jean-Philippe Brucker wrote: > [1] Virtio-iommu specification v0.9, sources and pdf > git://linux-arm.org/virtio-iommu.git virtio-iommu/v0.9 > http://jpbrucker.net/virtio-iommu/spec/v0.9/virtio-iommu-v0.9.pdf Looking at this I wonder why it doesn't make the IOTLB visible to the guest. the UNMAP requests seem to require that the TLB is already flushed to make the unmap visible. I think that will cost significant performance for both, vfio and dma-iommu use-cases which both do (vfio at least to some degree), deferred flushing. I also wonder whether the protocol should implement a protocol version handshake and iommu-feature set queries. > [3] git://linux-arm.org/linux-jpb.git virtio-iommu/v0.9.1 > git://linux-arm.org/kvmtool-jpb.git virtio-iommu/v0.9 Unfortunatly gitweb seems to be broken on linux-arm.org. What is missing in this patch-set to make this work on x86? Regards, Joerg From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.4 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BA8CC04EB8 for ; Wed, 12 Dec 2018 10:35:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ECC7C20849 for ; Wed, 12 Dec 2018 10:35:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ECC7C20849 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=8bytes.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-pci-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726925AbeLLKfr (ORCPT ); Wed, 12 Dec 2018 05:35:47 -0500 Received: from 8bytes.org ([81.169.241.247]:53762 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726877AbeLLKfr (ORCPT ); Wed, 12 Dec 2018 05:35:47 -0500 Received: by theia.8bytes.org (Postfix, from userid 1000) id 88ECF3D8; Wed, 12 Dec 2018 11:35:45 +0100 (CET) Date: Wed, 12 Dec 2018 11:35:45 +0100 From: Joerg Roedel To: Jean-Philippe Brucker Cc: iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, virtualization@lists.linux-foundation.org, virtio-dev@lists.oasis-open.org, mst@redhat.com, jasowang@redhat.com, robh+dt@kernel.org, mark.rutland@arm.com, bhelgaas@google.com, frowand.list@gmail.com, kvmarm@lists.cs.columbia.edu, eric.auger@redhat.com, tnowicki@caviumnetworks.com, kevin.tian@intel.com, marc.zyngier@arm.com, robin.murphy@arm.com, will.deacon@arm.com, lorenzo.pieralisi@arm.com, bharat.bhushan@nxp.com Subject: Re: [PATCH v6 0/7] Add virtio-iommu driver Message-ID: <20181212103545.GV16835@8bytes.org> References: <20181211182104.18241-1-jean-philippe.brucker@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181211182104.18241-1-jean-philippe.brucker@arm.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Hi, to make progress on this, we should first agree on the protocol used between guest and host. I have a few points to discuss on the protocol first. On Tue, Dec 11, 2018 at 06:20:57PM +0000, Jean-Philippe Brucker wrote: > [1] Virtio-iommu specification v0.9, sources and pdf > git://linux-arm.org/virtio-iommu.git virtio-iommu/v0.9 > http://jpbrucker.net/virtio-iommu/spec/v0.9/virtio-iommu-v0.9.pdf Looking at this I wonder why it doesn't make the IOTLB visible to the guest. the UNMAP requests seem to require that the TLB is already flushed to make the unmap visible. I think that will cost significant performance for both, vfio and dma-iommu use-cases which both do (vfio at least to some degree), deferred flushing. I also wonder whether the protocol should implement a protocol version handshake and iommu-feature set queries. > [3] git://linux-arm.org/linux-jpb.git virtio-iommu/v0.9.1 > git://linux-arm.org/kvmtool-jpb.git virtio-iommu/v0.9 Unfortunatly gitweb seems to be broken on linux-arm.org. What is missing in this patch-set to make this work on x86? Regards, Joerg